1. Field of the Invention
The present invention relates to a double-side scan device, and more particularly, to a double-side scan device capable of reversing a document to perform a double-side scan operation, and having a movable image scan module for performing a single-side scan operation or the double-side scan operation selectively.
2. Description of the Prior Art
When using a single-side scan device to scan two sides of a sheet of paper, it is required to reverse the paper manually after one side or surface is scanned, in order to scan the other side. This single-side scan operation is slow, and also has a difficulty of conveying the paper in different directions. Thus, a double-side scan device developed by prior art can automatically scan two sides (surfaces) of the paper, and the two sides of the paper can be scanned quickly, and the problem of conveying the paper in different directions can be solved.
A conventional design uses two scan modules to respectively scan the two sides of the paper in the double-side scan device, such as U.S. Pat. No. 4,536,077 and No. 5,680,204, but this design results in a large volume of the double-side scan device and high cost with the two scan modules. Thus, a design for reversing the paper to perform the double-side scan operation is provided, such as U.S. Pat. No. 5,430,536, which uses an interlacing path to connect an entrance section and an exit section of a paper conveying path. When a first surface or side of the paper is printed or scanned, a paper conveyer will move the paper back to the interlacing path, and the paper will return to the paper conveying path from the interlacing path to print or scan the second surface or side. However, this design requires the paper to repeatedly travel through the whole paper conveying path so that the moving path becomes longer and takes more time. Furthermore, the order of the papers will be reversed at the paper exit tray, and the user must re-collate the papers.
Additionally, U.S. Pat. No. 5,438,435 discloses a double-side scan operation scheme. However, it has some drawbacks of having a complex document conveying path and requiring a precision paper guiding control device to prevent the paper from moving in the wrong path or getting jammed. Since the document conveying path is complex, there are many necessary paper conveying elements, and the above double-side scan operation scheme suffers from high manufacturing cost.